Carburetor



Aug. 11, 1948. G. E. BEARDSLEY, JR Y 2,447,26

CARBURETOR I '3 Sheets-Sheet 1 Filed Feb. 10, 1939 INVENTOR. 'qffieardvJr:

dRNEY.

Aug. 17, 1948. G. E. BEARDSLEY, Jk

CARBURETOR 3 Sheets-Sheet 2 Filed Feb. 10, 1939 INVENTQR. 60ffieardr/eyJ/r 6k A ORNEY.

Aug. 17, 1948. e. E. BEARDSLEY, JR 2,447,254

CARBURETOR 3' Sheets-Sheet 3 Filed Feb. 10, 1939 INVENTOR. 60 1EfiM/dI/e JA' Patented Aug. 17, 1948 Guy E; Beardsley,

signor to Bendix In, West mimosa, coma, as-

A'viation Corporation; South Bend, 1116., a corporation of Delaware"Application Februarylo, 1939, Serial No. 255,676 -23 Claims. (01.261-41) My invention relates to carburetors.

My invention has among its objects to provide an improved carburetor ofthe economizer type wherein the mixture strength is controlled in animproved manner. A further object of my invention is to provide improvedmeans for controlling the richness of the fuel mixture in such acarburetor in such an improved manner as,

while obtaining the desired results as regards economy under normaloperation, also suppresses detonation while operating efficiently over awider range of power outputs, and obtaining improved engine operationwhile operating in the economizer range, 1. e., at high power outputs.

A still further object of my invention is to provide such an improvedcarburetor construction having the advantages aforesaid and furtherutilizing as a mixture controlling factor, pressures varyingproportionally with and in response to variations in the quantity of airflow ing to the engine, and thereby providing a more accurate measure ofthe power output than obtainable in prior devices.

'Still another object of my invention is to provide such an improvedeconomizer-equipped carburetor which is especially adapted to use insupercharged engines, and particularly in airplane engines, and tomaintain an improved control of the enrichment flow throughout highengine power output conditions regardless of changes in. superchargerspeed, or supercharger pressure rise or engine loads within theeconomizer range.

Another object of my invention is to provide such an improved carburetorwherein the economizer is controlled by the differential of throat andscoop pressures in such manner as to be operated proportionally with andin response to changes in the same differential of pressures controllingthe fuel inlet valve of the carburetor, and thereby effect furtheropening movement of said valve to enrich the mixture, in such mannerthat it is thus made possible by accurately measuring the air flow andutilizing this differential varying with the measured air flow to theengine, as the determinative factor controlling economizer operationunder high engine power output conditions, thereby, in effect, to makethe horsepower output of the engine this determinative factor.

Still further objects of my invention are to provide an improvedcarburetor wherein the main fuel flow controlling mechanism, which actsto maintain a constant fuel-air ratio, and my improved economizer areseparate and both are operated by variations in air How, and wherein, inthe economizer range, the economizer causes said main fuel flowcontrolling mechanism to be operated through an increasedrange ofopening movement; all 'in such'manner that the main fuel flowcontrolling mechanism ,notonly acts under all engine power outputconditions to" provide a known constant fuel-air ratio varying with theair flow, butis also caused to be additionally actuated in an openingdirection when ever the air flow controlled economizer comes intooperation, in such manner as to add to the inlet valve movementmaintaining a constant fuel-air ratio mixture, a further fuel enrichingincrement varying as a function of air flow under high engine poweroutput conditions. Other objects are to provide an improved carburetorof the above type wherein, while obtaining the above advantages, theinaccuracies of metering through a variable orifice are also eliminatedor confined to a small percentage of the total flow, and one wherein itis made possible for the operation of the carburetor to be readilymodified as desired to meet the varying requirements of diflerentengines, by making possible an independent adiustment of or a meresubstitution of a precalibrated, economizer element or elements,

' without disturbing the main fuel control mechanism, and a likeindependent adjustment or mere substitution for the main fuel flowcontrolling mechanism when only modification of the latter is required.

Still another object of my invention is to provide such an improvedeconomizer-equipped carburetor adapted to apply the above differentialcontrolling pressure to control the metering of either float typecarburetors or fuel pressure type carburetors of various forms whilebeing particularly adaptedto utilize this improved differential pressurecontrol to control the actuation of diaphragm actuated type fuelinlet'valves of such last-mentioned carburetors.

A still further object is to provide such an improvedeconomizer-equipped carburetor wherein the differential pressures atvarying power outputs may be automatically varied to compensate forchanges in altitudes, while also maintaining the desired relationshipbetween the main and enrichment flows.

Other objects and advantages of this invention will be apparent from thefollowing detailed description of several desirable embodimentsthereof,-considered in connection with the ac- 3 illustration only, andnot intended to define the scope of the invention, reference being hadfor that purpose to the subjoined claims.

In the drawings, wherein similar referencecharacters refer to similarparts throughout the several views:

Figure l is a vertical, diagrammatical, sectional view of a carburetoror charge forming device embodying the present invention;

Fig. la is a like detail view of a modified struction;

Fig. 2 is also a vertical, diagramxnatica l, sectional view of adifferent carburetor embodying a modified form of the invention, and

Fig. 3 is a vertical diagrammatical section of a carburetor embodying astill further modified form of the invention.

Referring to Figure 1, it will be observed that a carburetor bodysection I8 carries an air inlet passage or scoop I2 and forms aninduction passage I4. The induction passage is provided with a venturiI6, and a fuel discharge nozzle I8 is positioned somewhere near thesection of maximum restriction of the venturi I6.

The induction passage I4 is controlled by a throttle valve 28, which maybe manually operated from the pilot's or operator's compartment by meansof a'rod 22. The body section I8 of the carburetor is provided with aflange 24, by means of which it may be attached to the intake manifoldof an engine or to the inlet of a supercharger driven by the engine.

Fuel is supplied to the fuel discharge nozzle I8 by means of a fuelpassageway 26, which communicates with a fuel reservoir 28. The fuellevel in the reservoir 28 may be maintained at a substantially constantlevel by means of a fuel inlet passage 38, which is controlled by avalve member 32 actuated by means of a float mechanism 34. The flow offuel from the reservoir 28 to the fuel passageway 26 is controlled by arestricted passageway, herein a stationary metering or measuring orifice36 of fixed dimensions, and by a controlled orifice 38.

The orifice 38, communicating with the passageway 26, is controlled byan economizer valve 48. The valve 48 is carried by a diaphragm mechanism42, and is yieldingly urged downwardly to close the orifice 38 by meansof a spring 44 nested in a chamber 46. The chamber 46 is closed exceptfor a passageway 48, communicating with the fuel passageway 26,intermediate the fuel discharge nozzle I8 and the fuel reservoir 28. Thechamber 46 and the upper surface of the diaphragm 42 are thus subjectedto the pressure at a restricted section of the venturi I6, astransmitted through the fuel discharge nozzle I8 and the passageways 26and 48.

The fuel reservoir 28 and the lower surface of the diaphragm 42 aresubjected to the air pressure existent in the air inlet or scoop I2, bymeans of a passageway 58 interconnecting the fuel reservoir 28 throughan annular passage 58a connected to tubes or passageways 52 formed inthe air inlet or scoop I2.

The diaphragm 42, which actuates the economizer valve 48 controlling theorifice 38, is thus at the restricted section of the venturi I6, urgingit in a direction to open the valve 38. When this differential of fluidpressure creates a force willcient to overcome the force of the spring44, the

valve 48 opens the orifice 38 an amount proportional to the variation influid pressure, while opening of the valve 48 proportionally with and inresponse to changes in air fiow, also causes the float 34 to open thevalve 32 further in such manner as to increase the fiow through thelatter.

It will be noted that the pressure at the restricted section of theventuri I6, transmitted to the upper surface of the diaphragm 42 throughthe passages 26 and 48, is transmitted part of the Way through the fuelin the passageways; however, the fuel level may be lowered in thepassageway 48 by an amount equal to the suction at the restrictedsection of the venturi. It will be understood that, while the fuel inthe passage 48 is shown at the same level as in the float chamber 28,this is due to the closed position of the throttle 28 illustrated, andthat when the throttle is opened, the level of the fuel in passage 48will drop as the throttle opens; fuel flow, of course, then continuingthrough passage 26 and the throat pressure being transmitted to thediaphragm 42 through the fuel in the passage 26 and the air in thepassage 48.

It will thus be observed that with the Venturi suction and air scooppressure acting on the opposite sides of the orifice 36, the fuel nozzleI8 is always supplied with fuel during cruising under the control of thefioat34 and valve 32 through the restricted passageway 36 in such mannerthat a predetermined fuel-air ratio is maintained. These forces continueto act throughout the operation of the economizer valve 48' but thevalve 32 is caused to open further to supply an additional quantity offuel when the air scoop pressure and the Venturl suction reach apredetermined differential of pressure sufficient to open the valve 48.It will also be observed that the differential of pressure acting acrossthe orifice 36 varies with the differential of pressure causingoperation of the valve 48 and that once the economizer valve 48 hasopened to permit fiow through the orifice 38, the fuel fiow in any givenposition of the valve 48 would vary in the same proportion as thequantity of fuel fiowing through the orifice 38, i. e. in proportion tothe square root of the differential of pressures on opposite sides ofthe orifice; this same condition holding true for all positions of theeconomizer valve 48, until the differential of the pressures actingacross the diaphragm 42 drops to such a value that the spring 44 urgesthe valve 48 to completely close the orifice 38, whereupon thepreviously described control during cruising is resumed.

In Figure 1a, a modified construction utilizing the same economizervalve 48 is shown. In this construction, instead of the passage 48 beingconnected to the passage 26, the passage 48 is connected by a passage48a to an annular passage 48b which, in turn, is connected throughradially located passages 480 to a restricted portion, of the venturiI6. Further, it will be observed that in this construction, a bleedpassage 28a is connected between the passage 26 and a passage 26b whichis, in turn, connected by a restriction 260 to an annular passage 58a.In this construction, a higher suction effect is obtained for operationof the valve 48, while the bleed connection provided will function in awell-known manner to emulsify the fuel supplied through the nozzle I8.

pressures in the throat and constant fuel air ratio, and my economizermechanism are actuated by pressures varying proportionally with and inresponse to changes in said quantity, it is possible to control theenrichment of the fuel mixture in the economizer range with far greateraccuracy in accordance with known engine performance requirements thanhas heretofore been possible. Since I find that the air flow to theengine, while varying over a wide range at different power outputs,maintains a close relation -to the brake horsepower output, in myimproved mechanism I utilize these variations in air flow as acontrolling factor in fuel enrichment. More particularly, I utilize asthe controlling factor for the economizer the differential relationshipbetween the suction produced in the throat of the venturi and thepressure developed in the scoop, which differentia1 increases inproportion to the square of the air flow through the venturi. Thus, itwill be observed that the differential pressure resulting is such as tomake it possible to obtain a force exerted on a diaphragm in onedirection which bears a square relationship to the air flow through thecarburetor, and thereby obtain a correctly proportionedmixtureenrichment when the diaphragm is used to control the supply ofadditional fuel. Moreover, it will be recognized that it is possible, bymeans of automatic altitude compensating devices, to have such a forceexerted by the diaphragm proportional to the square of the mass air flow(weight per unit of time) at all altitudes, in suchmanner as and inresponse to changes in 6 open ends subjected to the pressure of the airentering the inlet passage or scoop;

The induction passage I3 is controlled by a manually actuated throttlevalve 23, controlled y the operator of the craft, It will be observedthat in this embodiment of the invention, fuel may be admitted into theinduction passage i3 to operate theeconomizer valve by balancing itagainst a spring of any chosen force and rate. As a result of thisconstruction, it will further be evident that it is possible to.approach very closely'the conditions established from engine tests asmore nearly approaching ideal engine fuel requirements, not only asregards actual economy of fuel consumption, butalso as regards increasedrange of economical operation at lower power outputs without detonation,all while continuing to suppress detonation'and obtain' =safe operationand improved efficiency through-operation at higher mean effectivepressures.-

"The embodiment of the invention illustrated on Figure'2 shows the sameapplied to a certain Bendix type of diaphragm operated carburetor havinga body section 9, an air inlet passage or scoop ll,"and an inductionpassage 13. A venturi'ji is positioned in the body section 9 and isprovided with an annular passageway I'I communicating with a restrictedsection of theventurijlby means of a plurality of apertures l9. Theannular passageway I1 is thus subjected .to the fluid pressureexistingat a restricted section of the venturi IS. A plurality of passageways2|, positioned in the air inlet passage or scoop II and only one ofwhich is shown, have their posterior to the throttle valve 23 by meansofa fuel discharge nozzle 25.

Fuel under pressure may be supplied to this carburetor by means of afuel conduit 21. Entry of fuel into the carburetor may be controlled .bya valve casing member 29 having apertures 3| therein. The apertures 3|may be controlled by a valve member 33 of a well known type normallybalanced by opposing pressures of the unmetered fuel flowingtherethrough, and carried on and actuated by a valve stem 35. Fuel underpressure is thus admitted from the conduit 21, through the apertures 5!controlled by valve member33, into a, chamber 31, separated from achamber 39 by means of a diaphragm assembly 4| carried by'the valve stem35. Fuel may be transmitted from the chamber 31 to the chamber 39 bymeans of a restricted orifice 43, corresponding to the orifices 36hereto described from whence it is delivered to the fuel nozzle 25 byway of a fuel conduit 45. The rate of fuel flow through the orifice 43is dependent, in part, on the variation in fuel pressure in chambers 51and 39, which are separated by the diaphragm valve. stem 35 may beactuated by a diaphragm- 5l, separating chambers 53 and 55.

The chamber 53 is connected by means of passageway 51, chamber 59 andpassageway 6i with the annular passageway l'l, subjected to the pressureat a restricted section of the venturi through the apertures l9. Thepassageway ii is provided with a restriction 63.

The chamber 55 is connected by means of passageway 65, chamber 61' andpassageway 69 to the passageways 2|, subjected to the pressure of theair at an unrestricted section of the air inlet passage or scoop I I,

It will'be observed that the passageways 9I- Y and 69 are interconnectedby means of a restricted orifice ll controlled by a valve 13. The valveI3 is adapted to be actuated to open and close the restricted orifice IIby means of a bell crank 15 operably connected to and actuated by ananeroid 11. The aneroid 11 may preferably bepositioned in the air inletpassage or scoop H, and thus subjected to variations in temperature andbarometric pressure in accordance with variations in altitude. It willbe noted that, as the pressure decreases with increasing altitude, theaneroid expands to the left, thereby actuating the bell crank 15 towithdraw the valve 13 from the orifice II to permit air to flow from thepassage 69 to the passage 6| to reduce the differential of fluidpressure between these two passages, and also between the chambers 55and 53, which actuate the fuel inlet valve 33.

The fuel chambers 31 and 39 may be separated from the regulator chambers53 and II by 7 means of a diaphragm 19 carried by the valve stem 35 toprevent leakage of air or fuel from one group of chambers to the other.Further, it will be noted that chamber 39 is connected by a passage 39ato a bottom chamber 39b which is separated from chamber 55 by adiaphragm 390 of the same area as diaphragm 19 in such manher as toequalize the pressure above and below these diaphragms so as to balanceout their effect on stem 35.

The operation of this device is as follows. When the unit is mounted onan aircraft or in any other installation wherein it may be used, aquantity of air is supplied to the air inlet passage or scoop The airpressure at the ends of tubes 2| is transmitted through the passageway69, chamber 61 and passageway 65 to chamber 55 of the regulator unit tourge the diaphragm connected to the valve stem 35, upwardly, as viewedin Figure 2, to open the fuel 4 admission valve 33 to admit fuel fromthe fuel conduit 21 to the chamber 31; a constant fuelalr ratio beingobtained as is well known in such pressure type carburetors.

The pressure of air in chamber 61 is exerted on the upper surface of thediaphragm 49 to help in urging the economizer valve 41 downwardlyagainst the resistance of a suitably loaded spring 3| nested in chamber59, to open the auxiliary fuel orifice 45a.

The greater portion of the air entering the air inlet passage or scoop Ipasses through the venturi l5, and a suction or reduction in pressure isdeveloped in the annular passageway IT by means of the apertures l9 inthe Venturi I5. This Venturi suction is transmitted through thepassageway 5|, restriction 63, chamber 59 and passageway 51 to thechamber 53 to exert a force on the diaphragm 5| tending to raise thevalve stem carrying the fuel admission valve 33, to

Since the chamber 59 is subjected to Venturi suction, the lower surfaceof diaphragm 49, which actuates the economizer valve 41 controlling theauxiliary fuel orifice a, is subjected to a suction force tending tourge the diaphragm downwardly to compress the spring 8| and open theauxiliary fuel orifice 45a, to admit an increased quantity of fuel tothe engine.

It will be noted that since fuel under pressure is supplied to thechamber 31 and is by-passed around the diaphragm 4|, by means of theorifices 43 and 45a, to the chamber 39, the diaphragm 4| is subjected toa force tending to close the fuel inlet valve 33; The pressure inchamber 31 must be greater than the pressure in chamber 39 in order forfuel to flow through the orifices 43 and 45a.

The fuel inlet valve 33, carried by the valve stem 35, is thus actuatedby air scoop pressure in chamber and Venturi suction in chamber 53. Whenthe force resulting from these two pressures exerted on the diaphragm5|, overcomes the force exerted by the variation in fuel pressure inchambers 31 and 39, urging the valve 33 toward the closed position, thediaphragm assembly moves upwardly, as viewed in Figure 2, to open thefuel inlet valve 33 to admit fuel to the chamber 31.

The pressure differential between fuel chambers 31 and 39, which is theforce across the metering orifices 43 and 45a, is determined by inchambers 53 and 55 acting on diaphragm 5|.

As the density of the air decreases due to increase in altitude, theaneroid 11 actuates the valve 13 to open the restricted orifice 1|,interconnecting the passageways GI and 59, to variably reduce thesuction in passageway BI and in chambers 59 and 53. The force urging theregulator diaphragm 5| upwardly to open the fuel inlet valve 33 is thusaffected by variations in altitude and by proper adjustment of theaneroid, linkage and orifices, this force may be held at substantially aconstant value for any chosen mass air flow regardless of changes inatmospheric density.

The auxiliary fuel orific 45a, which delivers an additional quantity offuel to the engine under certain operating conditions, is, as pointedout above, controlled by the economizer valve 41 and the diaphragm 49.When the force of air inlet pressure transmitted to the chamber 61 andthe force of the Venturi suction transmitted lower surfaces of thediaphragm 49 are sufficient to overcome the resistance of the spring 8|,urging the valve 41 to close the orifice 4511, the valve 41 is moveddownwardly, as viewed in Figure 2, to open the orifice 45a to admit anincreased quantity of fuel to the engine. It will be noted that theforce exerted on the diaphragm 49 to actuate the valve 41 is compensatedfor variations in altitude by means of the orifice 1|, interconnectingpassages 69 and GI, the aneroid controlled valve 13.

In this form of my invention, it will be observed that not only do thevariations in the quantity of the air flow to the engine, represented bythe differential between th throat and scoop pressures, control theeconomizer valve 41, but the latter valve also controls the action ofthe fuel inlet valve 33 in the economizer range to sllperimpose anenrichment flow on the constant fuel-air ratio main flow. Here it willbe noted that pressures from the throat and scoop also act on oppositesides of the diaphragm 5| carried by the stem 35 of the fuel inlet valve33, to control the position of the latter and the fuel pressure on theopposite sides of the diaphragm 4| at the same time that the economizervalve 41 also acts to control the fuel pressures on the opposite sidesof diaphragm 4| and the consequent supply of fuel to the nozzle 25.Thus, due to the provision of my improved economizer valve 41, it ismade possible to obtain a wholly new and more accurate control of thefuel valve 33 in accordance with engine requirements through modifyingthe control effected by the latter valve, as a result of the provisionof the additional orifice 45a controlling the flow inthe fuel lineleading to the nozzle 25 and also controlled by the valve 41. Moreparticularly, it will be observed that as the differential pressure actson the diaphragm 5| to open the valve 33, this same differentialpressure is acting on the economizer valve 41 to open the orifice 45a.Further, as this orifice is opened, flow downward through the latterincreases the pressure beneath the diaphragm 4| and therebysimultaneously correspondingly decreases the pressure above thisdiaphragm, in such manner as thus temporarily to unbalance the valvemechanism including the valve 33 and open the latter to increase therate of fuel flow through said valve and thereby torestore thfe.Attention is moreover directed to the fact that in my improvedeconomizer construe tion, the above pressure differential controlling"balance.

the economizer valve 41 is controlled bythe anelactuated by raid in suchmanner as thereby to provide automatic compensation for altitudebyautomatically varying, the differential of pressure acting on both thevalves 41 and 33. The embodiment of the invention illustrated in Figure3 is similar in many res ects to that illustrated in Figure 2, agenerally similar pressure carburetor adapted to obtain a constantfuel-air ratio, being illustrated and like parts separated by adiaphragm I9I, may be employed to assist in actuating the fuel inletvalve I33 in such manner as to enable the latter to function as aneconomizer. In this construction, I increase the ratio of thefuel-metering head between the chambers I31 and I39, across the fuelorifice I43 corresponding to orifices 36 and 43 previously described, tothe air metering head differential between air scoop III and Venturisuction at chamber II1. Downwardmovement of the diaphragm I9I is limitedby spaced stops I93 positioned in the chamber I89. The diaphragm iscentrally apertured to pass over the valve stem I35 and engages anabutment I95, when moved upwardly by fluid pressure acting on theexposed surface of the diaphragm -I9I outside 'of a pair of sealingbellows I91 and I99 positioned to engage the upper and lower surfaces ofthe diaphragm I9I in the chambers I 81 and I89 respectively. Thediaphragm I 9I is yielding y ur downwardly toward engagement with thestops I93 by means of a spring I98,

"The lower end of chamber I89, as viewed in Figure 3, is.clo'sed by adiaphragm I98, which forms the upper portion of a chamber I94. The

chamber I94 is interconnected by means of a fuel duct I92 with themetered fuel chamber I39, so that the pressure of the fuel in cham-.

bei- I39 is balanced against the pressure of fuel in chamber I94 bymeans of the equal area diaphragms I19 and I96 as described inconnection with Figure 2.

The chamber I81 is connected by means of a passageway I90 with theVenturi suction as transmitted to th chamber I53 by means of thepassageway I8I. The chamber I89 is connected by means of afpassagewayI88 with the air inlet or scoop pressure as transmitted to the chamberI55 by means of the passageway I69.

' In the operation of this device, when the total force of the air scooppressure in chamber I89 and the Venturi suction in chamber I 81 exertsufiicient upward force on the diaphragm I! to compress the spring I98,the upper surface of the diaphragm I9I engages the abutment I95, andthereafter exerts a force which, in addition to the force exerted onthediaphragm II by Venturi suction as transmitted to chamber I53 and airscoop pressure as transmitted to chamber I55, urges the fuel inlet valveI33 toward the open position to admit fuel to the fuel chamber I31. Whenthe force urging diaphragm I 9| upwardly drops below the downwrd forceexerted by'the spring I98, the diaphragm I9I is moved' valve member I13,controlling the restricted orifice I1 I, maybe employed to compensatethe fluid pressures in chambers I53 and I55 and I81 and I99 forvariations in altitude. If desired, however an altitude control featuremay be employed to compensate the forces acting on only one of thediaphragm I5I and I9I.

In this construction, it will be observed that substantially the sameresults are'obtainable as described above-in connection with .theconstruction shown in Figure 2, both as regards control of the pressurefuel inlet valve, here indicated at I33, and also as regards theautomatic compensation for altitude by the aneroid here indicated atI11. However, here it will be noted that the different pressures in theair passage means act directly on the diaphragm of valve I33 rather thanindirectly through an additional valve, as in Figure 2, wherein thediaphragm of valve 41 is acted on by these different pressures and, inturn, controls the valve 33. Further, it will be observed that theseresults are obtained while utilizing only this valve I33 and withoutrequiring the use of any additional valve such out of engagement withthe abutment I95 and I toward engagement with the stops-I93. Thereafter,the fuel inlet valve I33 isv controlled only by the diaphragm \I5I,as.pointed .out above.

It will be noted that the'aneroid actuated as the economizer valves 49and 41 heretofore described, and while requiring only the provision ofthe improved spring controlled diaphragm I9I which is itself acted uponby the differential pressures in proportion to those in the scoop IIIand the throat of Venturi I I5.

In all illustrative forms of my invention, it

will also beevident that, while during normal cruising the main fuelflow is through a fixed main orifice and varied in proportion to accu-vrately measured variations in air flow, the movement of the separateeconomizer diaphragm (42 in Figures 1 and 1a, 49 in Figure 2, and HI inFigure 3), which is stationary during normal fuel flow and movable onlyunder high power output conditions, causes a greater than normalopenin'g movement of the valve which controls the main fuel flow (32 inFigures 1 and la, 33 in Fig- -ure 2, and I33 in Figure 3). This furtheropening movement of this main fuel valve is controlled by the samevariations in air flow actuating said valve to effect the main fuelfiow, and this enrichment flow is superimposed on the fuel component ofthe main fuel-air ratio with both the enrichment flow and this fuel'component thereafter each continuing to vary independently with changesin air flow. The above action also takes place irrespective of whetherthe control of this main fuel valve is effected indirectly through thefuel acting on the valve actuating mechanism, as in Figures 1, 1a and 2,or directly mechanically on said mechanism as in Figure 3, and alsoirrespective of whether the additional fuel is delivered through afixed. main orifice and variable economizer orifice as in Figures 1, 1aand 2, or through a single fixed main orifice as in Figure 3.

As a result of my invention, it is also made possible in all formsthereof to provide fuel metering orifice means for the main fuel flowwhich are fixed against orifice area varying movement in response tochanges in engine operation, and

whereby the cross sectional area is maintained constant in such mannerthat the inaccuracies in the main fuel flow resulting from such changesin areaare avoided at all times. Thus, in Figures 1 and 1a, such anon-variable orifice 38 is made possible,'whi1e a like orifice 43 isprovided in Fig. 2, and the single orifice I43 in Fig. 3 is also fixedagainst movement causing variations in flow therethrough. As a result,it is not only made possible to simplify the main fuel flow orificestructure to the maximum degree, but also markedly to increase theaccuracy of the constant fuel air ratio flow therethrough. This last isvery important under conditions where the fuel air ratio is of criticalimportance, for example, enabling cruising lean under conditions where,with the inaccuracies inherent in a variable orifice, cruising richwould Otherwise be required. Further. my improved construction alsomakes it possible for this same increased accuracy to be obtainedthroughout the entire range of engine loads, this markedly more accuratemain fuel flow continuing to be obtained irrespective of the provisionof my air fiow controlled economizer and irrespective of whether theengine is operating under normal load conditions without the economizeror under overload conditions with the economizer in operation. Accuracyof metering when operating under overload conditions with the economizerin operation, is also very important, enabling satisfactory engineoperation under conditions impossible with inaccurate metering. Thus, itis made possible, for example, under-critical or emergency overloadconditions for airplane engines of high output to attain maximumhorsepower despite the fact that engine operation is such that slightvariations from the correct amount of fuel will produce either dangerousoperation on the one hand, due, for example, to overheating ordetonation, or obviously unsatisfactory operation .on the other hand,due, for example, to loss in engine power and engine roughness. Thus,with the enrichment flow constituting only a'fraction of the total fiow,and with the total fiow (Fig. 3), or all but this fraction of the totalflow (Figs. 1, 1a and 2), accurately meterable by non-variableprecalibrated orifice means, and each of the main and enrichment flowsresponsive sensitively to the same controlling factor, namely, tovariation in the same differential of airflow, an extremely sensitiveand accurate fuel supply to the engine is maintained over the wholerange of engine performance.

Attention is also directed to the fact that, throughmy improved separateyet cooperating and coordinated air flow controlled controllingmechanism for the normal cru sing and the mixture enrichment flows, itis thus made possible to elimina e or confine to a small percentage ofthe total fiow, i. e. to the enrichment flow, the inaccuracies ofmetering through a variable orifice, and thereby obta n a fuel su p ywhich under all conditions verv closely approximates the requirementsfor ideal theoretical engine performance. Further, my improvements makeit possible for the fuel fiow during economizer operation to be, ineffect, divided into two components. one compr sing a known normal fuelflow through a fixed orifice and controlled in response to variations inair flow by the main fuel flow controlling mechanism and whichcontributes a flow of known fuel air ratio, and the other comprising aknown enrichment fiow which is added to the main fuel flow by theseparately controlled and operated economizer mechanism. Both areoperated in the economizer range by pressures responsive ot variationsin air flow, all in such manner that in the latter range the total orenriched flow is accurately controlled by the air flow. Also, eachmechanism being separate is accordingly separately adjustable whenadjustment is required, each without requiring adjustment of the other.Attention is also directed to the fact that all forms of my improvedeconomizer mechanism also act in the economizer range in the manner of abooster to increase the opening movement of the main fuel flowcontrolling mechanism, this being accomplished in the forms shown inFigures 1, 1a and 2 by increasing the size of the fuel measuring orificemeans through the provision of an additional measuring orifice openedonly in the economizer range, and being accomplished in the form shownin Figure 3, by

increasing the force available to operate the main fuel controlling valvthrough the additional air pressure responsive diaphragm which also actsthereon only in this range. Further, my improvements also make itpossible readily to apply my improved economizer mechanism to eitherfloat carburetors, such, for example, as illustrated in Figures 1 and1a, or pressure carburetors such as illustrated in Figures 2 and 3. Italso makes it possible to do this without major changes in standardcarburetors of either type, or requiring either that the main fuel fiowbe upset in the economizer range, or the use of a variable orifice inthe main fuel flow, or a common variable orifice for the combined mainand enrichment fuel flows, or the provision of both a variable orificein the main fuel flow only and an additional fuel venturi in the mainfuel flow.

In addition to the advantages set forth above, attention is alsodirected to the fact that in my improved construction th economizer isfreed from the objectionable variables affecting the operation of theeconomizer, and of the engine, which are inherent in superchargers,such, for example, as the variations in engine speed which characterizeprevious supercharger rise and supercharger discharge pressure operatedeconomizers. Since, as a result of these variables, neither the pressurerise through a supercharger nor the discharge pressure of a superchargermaintains a constant proportionality tothe metering suction ordifferential between the throat and scoop in the carburetor, theenrichment effected by an economizer of either of these types thus bearsno fixed relation to the quantity of air supplied to the engine. In myimproved construction, however, the economizer is wholly independent ofthese. objectionable variables and, since it varies the enrichmentproportionally with and in response to changes in the metering suctionor differential of throat and scoop pressures, and, irrespective ofchanges in engine speed, the enrichment accordingly variesproportionally with and in response to changes in the quantity of airflowing to the engine, 1. e. in proportion to engine requirements.Moreover, in my improved construction, my new proportionality ofenrichment is also maintained, and by a single aneroid, irrespective ofvariations in altitude or temperature. Further, my improvedproportionality of enrichment is obtained irrespective of whether asupercharger is used or not and, if a supercharger is used, whether thesame is located posterior to or anterior to. the throttle.

While the invention has been described with particular reference to afew illustrative embodiments, it is to be understood that many changesmay be made in the details of construction without departing from thespirit of the invention as defined by the following claims.

What I claim as new and desire to secure by Letters Patent is:

1. A charge forming device for an internal combustion engine comprisinga conduit for supplying air to the engine, a throttle controlling 13 thesame, air flow measuring means including venturi located in said conduitupstream of the throttle for setting up a differential in the airpressures at two spaced points in the conduit proportional to thequantity of air flowing through said conduit. a fuel conduit forsupplying fuel to the engine, a fuel valve controlling the fiow of fuelthrough the fuel conduit, a fuel metering orifice in the fuel conduit,means including passages extending from the venturi at said spacedpoints for establishing a differential in the pressures at spaced pointsin said fuel conduit on opposite sides of the metering orifice therebyto provide fuel flow at a rate substantiall proportional to air flow, aby-pass around said. orifice, an economizer valve controlling saidby-pass, a movable wall operatively connected to said economizer valve,and pressure trans,- mitting means interconnecting the oppositesides ofsaid Wall with one of said conduits at the said spaced points therein 2.The invention defined in claim 1 wherein said means for establishing adifferential in the pressures at spaced points in said fuel conduitincludes a plurality of diaphragms operatively connected to said fuelvalve and responsive to said diiferential in air pressures and to thedifferential in the fuel pressures on opposite sides of said meteringorifice.

3. The invention defined in claim 1 comprising in addition a constantlevel fuel chamber in the fuel conduit between the fuel valve and themetering orifice, and a float in the chamber for actuating said fuelvalve, said fuel conduit discharging substantially at the throat of saidventuri and forming one of said passages and a duct leading from theentrance of the venturi to the top of the constant level chamber forminganother of said passages. I

- 4. A device for controlling the supply of fuel to an engine comprisinga main air conduit for supplying air to the engine, air flow measuringmeans including a venturi located in said conduit for setting up adifferential in the air pressures at two spaced points in the conduitproportional to the quantity of air flowing through Y said conduit, afuel conduit for supplying fuel to the engine, a fuel valve controllingthe flow of fuel through the fuel conduit, a fuel metering orifice inthe fuel conduit, means including passages extending from the venturi atsaid spaced points for establishing a differential in the pressures atspaced points in said fuel conduit on opposite sides of the meteringorifice thereby to provide fuel flow at a rate substantiallyproportional to air fiow, an additional orifice in parallel with saidmetering orifice, an economizer valve controlling said additionalorifice and biased toward closed position, a movable wall operativelyconnected to said economizer valve, and pressure transmitting meansinterconnecting the opposite sides of said wall with one of saidconduits at the said spaced points therein for opening said economizervalve to enrich the mixture during high power output conditions.

5. A device for controlling the supply of fuel to an engine comprising aconduit forsupplying air to the engine, a throttle controlling the same,air flow measuring means including a venturi located in said conduitupstream of the throttle for setting up a differential in the airpressures I 14 through the fuel conduit, a fuel metering orifice in thefuel conduit for creating a differential in the fuel pressures at twospaced points in the fuel conduit proportional to the fuel flowingthrough said orifice, means responsive to said airv and fueldifferential pressures for controlling said valve to regulate the fuelflow and thereby to maintain the differential in fuel pressuresproportional to the differential in air pressures, a icy-pass aroundsaid orifice, an economizer valve controlling said by-pass, a movablewall operatively connected to said economizer valve, and pressuretransmitting means interconnecting the opposite sides of said wall withone of said conduits at the said spaced points therein.

6. A charge forming device'for an engine having an air conduit, athrottle in the conduit, an air differential pressure creating means inthe conduit anterior to the throttle, a fuel conduit receiving fuel froma source and supplying it to the engine, fuel metering means in saidfuel con duit for creating a fuel differential pressure in said fuelconduit upon fiow of fuel therethrough, valve means for controlling theflow of fuel through the conduit; a plurality of diaphragms connected tothe valve means for operating the same, means for subjecting thediaphragms to the airand fuel differential pressures, an enrichmentvalve for varying the effective area of the fuel metering means, adiaphragm operatively connected to the enrichment valve, and passagesinterconnecting the last-named diaphragm and one of said conduits forsubjecting the last-named diaphragm to one of said differentialpressures,

' said diaphragm operated enrichment valve being inoperative at lowvalues of said one differential pressure corresponding to low poweroutput and being arranged to open when said one differential pressureexceeds a predetermined value corresponding to a relatively high poweroutput'of the engine. t I

7. A charge forming device having fuel supply passage means includingmetering orifice means fixed against orifice area varying-movement inresponse to changes in engine operation, air flow passage meansincluding venturi means having a throat and a scoop, a fuel inlet valvein said fuel supply passage means normally balanced by opposingpressures of unmetered fuel being de-' livered to said orifice means,valve w actuating means including a plurality of diaphragms coaxial withsaid valve and forming movable walls of four chambers for maintaining asubstantially constant fuel air ratio and having one diaphragm fixed atits periphery and subjected on opposite sides to air pressures in saidthroat and scoop and another diaphragm fixed at its periphery and spacedbetween said first mentioned diaphragm and said valve and subjected onopposite sides to the metered and unmetered fuel pressures on oppositesides of said orifice means, an economizer mechanism for enriching themixture under high engine power output conditions including a pressureresponsive movable wall biased against mixture enriching movement duringnormal engine power output conditions, and pressure transmittingconnections from the opposite sides of said movable wall to two of thesaid chambers for subjecting the movable wall to a differential inpressures proportional to the differential in the pressures in saidthroat and scoop thereby to actuate the wall and enrich the mixture whensaid difierential in the pressures in said throat and scoop exceeds apredetermined value.

an engine comprising fuel supply passage means including a meteringorifice fixed against orifice area varying movement in response tochanges in engine operation, an air supply passage including means forsetting up a differential of pressures proportional to air fiow, valvemechanism including a fuel valve in said fuel supply passage meansmovable to vary the supply of fuel to said orifice, valve actuatingmeans including a plurality of diaphragms movable with said valve formaintaining a substantially constant fuel air ratio and movable inresponse to changes in said differential of pressures in said airpassage means, one of said diaphragms being subjected to said pressuresand another to fuel pressures on opposite sides of said orifice, aneconomizer means for controlling the operation of said valve actuatingmeans to effect further fuel valve displacement to increase the fuelflow through said fuel supply passage means to enrich the mixture, saideconomizer means being actuated by a movable wall subjected on oppositesides to two of the pressures to which said diaphragms are subjectedhaving a differential proportional to said differential of pressures.

9. The invention defined in claim 8 wherein said economizer meansincludes a by-pass around said metering orifice, and an economizer valvein said by-pass biased toward closed position and mechanically connectedto said movable wall to be opened thereby under conditions of higherthan normal power output.

10. A device for controlling the supply of fuel to an engine comprisingan air supply conduit having means therein for creating a differentialin air pressures in response to fiow of air therethrough, a fuel conduithaving fuel metering means therein for creating a differential in fuelpressures in response to the fuel fiow therethrough, a valve controllingthe fiow of fuel through the fuel conduit, means including an aneroidfor establishing a modified differential in air pressures proportionalto the air mass rate of flow through the air conduit, a plurality ofdiaphragms operatively connected to said valves and forming movablewalls of four chambers, means for subjecting two of the chambers to saidmodified air pressures and the other two chambers to said fuelpressures, an element for varying the effective area of the fuelmetering means and biased against area increasing movement, a movablewall operatively connected to said element, and pressure transmittingmeans connecting the opposite sides of said movable wall with two ofsaid chambers for subjecting the wall to a differential pressure varyingproportionally with said modified differential in air pressures therebyto increase the effective area of the fuel metering means when the airmass rate of flow exceeds a predetermined value.

11. A device for controlling the supply of fuel to an engine comprisinga conduit for supplying air to the engine, a throttle controlling thesame, air flow measuring means including a venturi located in saidconduit upstream of the throttle for setting up a differential in theair pressures at two spaced points in the conduit proportional to thequantity of air flowing through said conduit, a fuel conduit terminatingin a nozzle dischargin in said air conduit, a fuel valve controlling thefiow of fuel through the fuel conduit, a fuel metering orifice in thefuel conduit for creating a differential in the fuel pressures at twospaced points in the fuel. conduit proportional to the fuel flowingthrough said orifice, means responsive to said air and fuel differentialpressures for controlling said valve to regulate the fuel flow andthereby to maintain the differential in fuel pressures proportionally tothe differential in air pressures, a by-pass around said orifice, aneconomizer valve controlling said bypass, a movable wall operativelyconnected to said economizer valve, and pressure transmitting meansinterconnecting the opposite sides of said wall with one of saidconduits at spaced points upstream from said nozzle at which adifferential in pressures is established by and proportional to the flowtherein, thereby subjecting the wall to a differential in fluidpressures varying with r' changes in air flow so as to open saideconomizer valve at a predetermined mass air ficw regardless of enginespeed or throttle position.

12. A device for controlling the supply of fuel to an engine comprisingan air supply passage, a venturi in said passage for establishing a pairof air pressures having a differential proportional to the air flow tothe engine, a fuel supply passage, a fuel metering orifice in the fuelsupply passage fixed against orifice area varying movement in responseto changes in engine operation, a fuel valve in the fuel passage, meansresponsive to said differential in air pressures for controlling saidvalve to supply fuel through said orifice at a rate establishing a pairof fuel pressures on opposite sides of said orifice having adifferential in predetermined ratio to said differential in airpressures and proportional to the air flow to the engine, and mixtureenrichment mechanism operative under higher than normal power outputconditions including an additional fuel orifice in parallel with saidmetering orifice, an enrichment valve controlling the flow through saidadditional orifice, a spring yieldingly holding said enrichment valve inclosed position, a movable wall connected to said enrichment valve, andpressure communicating means interconnecting each side of said wall withone of said supply passages for subjecting said wall to one of saidpairs of pressures for opening said enrichment valve against the forceof said spring.

13. A device for controlling the supply of fuel to an engine comprisingan air conduit for supplying air to the engine, means in the air conduitfor establishing two air pressures having a differential varyingproportionally with the rate of air fiow through the conduit, a fuelconduit for supplying fuel to the engine, fuel metering orifice means inthe fuel conduit for establishing two fuel pressures having adifferential varying proportionally with the fuel flow therethrough, afuel valve movable to vary the supply of fuel to the fuel meteringmeans, valve actuating means including a plurality of diaphragmssubjected to said fuel and air differential pressures in such manner asto be urged in one direction by said air differential pressure balancedby the fuel differential pressure urging the diaphragms in the oppositedirection, and means operative only during high engine power outputconditions for unbalancing said diaphragms and effecting displacement ofsaid valve to increase the fuel fiow through said valve to enrich themixture and restore the balance of said diaphragms in the new positionof the valve, said last named means including a by-pass around said fuelmetering orifice means, and an economizer valve normally closing saidby-pass andactuated in a valve opening direction by a movable wallhaving pressure transmitting connections from each side thereof to oneof said conduits for subjecting said wall to two of said pressures thedifferential of which is proportional to said differential in airpressures.

14. A carburetor comprising a fuel supply passage receiving fuel from asource under pressure and including a fuel metering orifim having anormally fixed area for setting up a differential in fuel pressures onopposite sides of said orifice -in response to flow therethrough, an airflow pasment mechanism for effecting further displacement of said fuelvalve to produce an enrichment of the mixture during higher than normalpower engine operating conditions, said mixture enrichment mechanismincluding a by-pass around said fuel orifice, a spring pressedeconomizer valve normally closing said by-pass, a movable wall connectedto the economizer valve, and means intercommunicating each of the sidesof said movable wall with one of said passages and subjecting the wallto two of said pressures having a differential varying with ,andproportional to air fiow through the air flow passage regardless ofvariations in engine speed or throttle position.

15. In a carburetor: air supply passage means including a throttle,Venturi means having a throat of fixed cross-sectional area in allthrottle positions, and a scoop; fuel supply passage means includingstationary unobstructed metering orifice means of constant metering areain all throttle positions; fuel flow controlling means having air fiowconnections to both said throat and scoop, inlet valve means for varyingthe fuel fiow to said orifice means, and means responsive to changes inthe pressures in said throat and scoop for automatically controllingsaid inlet valve means to maintain a fuel flow through said orificemeans for a substantially constant fuel air ratio mixture under bothnormaland high engine power output conditions; and mixture enrichmentmechanism having means for increasing the fuel flow including a movablemember movable to control the action of said inlet valve means to enrichthe mixture, a valve actuatin diaphragm having one side thereof actedupon by pressure from the throat and the other side thereof by pressurefrom the scoop whereby said diaphragm is movable proportionally with andin response to changes in said throat and scoop pressures, and springloading means for preventing movement of said member by said diaphragmto effect such enrichment save underhigh engine power output conditions.

16. A carburetor having fuel suppl passage means including meteringorifice. means fixed against orifice area varying movement in re sponseto changes in engine operation, air supply passage means includingVenturi means having a throat and a scoop, fuel flow controllingmechanism having air fiow connections to both said throat and scoop,means automatically movable in response to variations in thedifferential of air pressures in said throat and scoop, and inlet valvemeans controlled by said last mentioned means for controlling the fuelsupplied to said orifice means to maintain a fuel flow for asubstantially constant fuel air ratio mixture 18 under both normal andhigh engine power output conditions, and economizer mechanism havinadditional pressure responsive means acted, upon by air pressures fromsaid throat and scoopxand movable in response to variations in saiddifferential of pressures to control said inlet valve.

means to supply additional fuel and enrich the mixture, and meansnormally biasing said additional pressure responsive means againstmovement to enrich the mixture and enabling such movement thereof onlyunder high engine power output conditions. 1'7. A carburetor having fuelsupply passage means including metering orifice means fixed againstorifice area varying movement in response to changes in engineoperation, air suppl passage means including Venturi means having athroat and an air scoop, fuel flow controlling means having air flowconnections to both said throat and scoop, means automaticallyresponsive to changes in the differential of air pressures in saidthroat and scoop, and inlet valve means controlled by said lastmentioned means for controlling the fuel flow to said orifice'means' tomaintain a fuel flow for a substantially constant fuel air ratio mixtureunder both normal and high engine power output conditions, and mix-.

ture enrichment mechanism including an additional orifice in parallelwith said orifice means, a movable element movable to control the fuelflow through said additional orifice and thereby control said inletvalve means to enrich the mixture, actuating means for said elementhaving a pressure responsive member having 'opposite faces respectivelysubject to air pressures from said throat and scoop, and means normallybiasing said element against movement to enrich the mixture andpermitting movement of the latter only under higher than normal enginepower output conditions.

18. A carburetor having fuel supply passage means including meteringorifice means fixed against orifice area varying movement in response tochanges in engine operation, air supply passage means upstream from thethrottle including means for setting up a differential of pressuresproportional to air fiow, valve mechanism including a fuel inlet valvein said fuel supply passage means movable to vary the supply of fuel tosaid orifice means and normally balanced by opposing pressures ofunmetered fuel being delivered to said orifice means, valve actuatingmeans responsive to changes in said differential of pressures in saidair passage means and normally balanced by fuel pressures on oppositesides of said orifice means for maintaining a substantiall constant fuelair ratio, economizer means for effecting an increased fuel flowthroughsaid fuel supply passage means to enrich the mixture and likewisecontrolled by changes in said differential of pressures, and pressureresponsive means for modifying the action of said differential ofpressures on said actuating means and on said economizer means inaccordance with variations in the density of the air in said air flowpassage means at different altitudes.

19. A carburetor having fuel supply passage means including meteringorifice means fixed against orifice area varying movement in response tochanges in engine operation, air supply passage means including meansfor setting up a differential of pressures proportional to air fiow,valve mechanism including a fuel inlet valve in said Euel supply passagemeans movable to vary the supply of fuel to said orifice means and nor-19 mally balanced by opposing pressures of unmetered fuel beingdelivered to said orifice means, valve actuating means responsive tochanges in said differential of pressures insaid air passage means andnormally balanced by fuel pressures on opposite sides of said orificemeans for maintaining a substantially .constant fuel air ratio,economizer means responsive to changes in said differential of pressuresin said air passage means for producing an unbalance of said valveactuating means and effecting displacement of said valve to increase thefuel fiow to enrich the mixture, and pressure responsivemeans'responsive to changes in pressure in said airpassage means due toaltitude for modifying the action of said difierential of pressuresonusaid actuating means and on said economizer means in accordance withvariations in altitude.

20. In a carburetor, air supply passage means including Venturi meanshaving a throat and a scoop, fuel supply passage means including fuelmetering orifice means fixed against orifice area Varying movement inresponse to changes in en- 20 and having a plurality of valve actuatingdiaphragms coaxial with said valve, means for subjecting the oppositesides of one of said diaphragms to pressures from said throat and scoop,means for subjecting another of said diaphragms to the fuel pressures'onopposite sides of said orifice means, means for subjecting oppositesides of a third diaphragm of said coaxial diaphragms to pressuresvarying proportionally with and in response to pressure changes in saidthroat and scoop, and means normally preventing the actuation of saidvalve by said third diaphragm and enabling actuation of said valvethereby to supply additional 'fuel only under high gine operation and anozzle projecting into said throat, and fuel fiow controlling mechanismfor maintaining a substantially constant fuel air ratio at any constantpressure and temperature of the air entering said air passage meansincluding a fuel inlet valve and valve actuating mechanism includingmeans for maintaining the fuel on opposite sides of said fuel orificemeans subjected to pressures from said throat and scoop, and economizermechanism havin a valve controlling the operation of said fuel flowcontrolling mechanism to effect the flow of additional fuel through saidnozzle to enrich the mixture, and valve actuating means movableproportionally with and in response to variations in the differential ofpressures in said throat and scoop and operative only under high enginepower output conditions.

21. In a carburetor, air supply passage means including Venturimechanism having a throat and a scoop, fuel supply passage meansincluding a fuel chamber, fuel metering orifice means fixed againstorifice area varying movement in response to changes in engine operationand leading from said chamber, and a nozzle projecting into said throat,fuel fiow controlling mechanism for maintaining a substantially constantfuel air ratio at any constant pressure and temperature of the airentering said air passage means including a fuel inlet valve and valveactuating mechanism including means for maintaining a substantiallyconstant, level in said chamben and also having the fuel pressures onopposite sides of said orifice means varying with the throat and scooppressures, an economizer valve biased to closed position and operable tocontrol said controlling mechanism to increase the flow through saidnozzle to enrich the mixture, and economizer valve actuating meansmovable proportionally with and in response to variations in thedifferential of pressures in said throat and scoop to open saideconomizer valve only under high engine power output conditions.

22. A carburetor having fuel supply passage means including meteringorifice means fixed against orifice area varying movement in response tochanges in engine operation, air supply passage means including Venturimeans having a throat and a scoop, a fuel inlet valve controlling thefiow through said orifice means and normally balanced byopposingpressures of unmetered fuel being delivered to said orificemeans engine power output conditions.

23. A charge forming device for an internal combustion .enginecomprising a passage for supplying air to the engine, a throttlecontrolling the same, air differential pressure creating means in saidpassage anterior to the throttle for setting up a differential of airpressures varying proportionally with the quantity of air flowingthrough said passage throughout the entire range of engine operation, afuel conduit for introducing fuel into the engine, valve meanscontrolling the flow of fuel through said conduit, a fuel meteringorifice in said fuel conduit for creating a fuel differential pressuretherein, means responsive to changes in said differential of airpressures for effecting displacement of said valve means to deliverthrough said orifice sufficient fuel to produce a predetermined fuel airratio during normal engine power output conditions and during highengine power output conditions, and mixture enrichment mechanism biasedagainst operation save under higher than normal engine power outputconditions and including additional fluid pressure responsive means,subject to pressures producing a differential of pressures varyingproportionally with and in response to changes in said differential ofair pressures throughout high engine power output conditions, forefi'ecting further displacement of said valve means to superimpose onsaid predetermined fuel air ratio an increased fuel flow producing'anenrichment of the mixture, and having said additional pressureresponsive means movable while said first mentioned pressure responsivemeans continues to effect its own displacement of said valve means, saidmixture enrichment mechanism also having open passages connecting theopposite sides of said additional pressure responsive means withopposite sides of said orifice, and said mechanism also including aby-pass around said orifice, and a valve actuated by said additionalpressure responsive means and varying the opening of said by-passproportionally with and in response to the drop across \said airdifferential pressure creating means.

GUY E. BEARDSLEY, Ja.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS (Other references on following page) Number NumberFOREIGN PATENTS Country Date Great Britain Sept. 18, 1912 Great BritainSept. 26, 1918 Great Britain May 1, 1919 Great Britain Jan. 20, 1921Great Britain Apr. 15, 1937 Great Britain Sept. 6, 1937 Great BritainJuly 25, 1940 France Nov. 10, 1922 France May 4, 1922 France Mar. 24,1938 Austria Sept. 10, 1925 Italy Jan. 20, 1939 Certificate ofCorrection Patent No. 2,447,264.

GUY E. BEARDSLEY, JR.

It is hereby certified that errors appear in the printed specificationof the above numbered patent requiring correction as follows:

Column 6, line 26, for orifices 36 hereto read orifice 86 heretofore;column 9, line 69, for downwrd read downward; column 11, line 49, formechanism read mechanisms; line 69, for 0t read to; column 15, line 45,claim 10, for valves read valve; column 18, line 61, claim 18, andcolumn 19, line 13, claim 19, for pressure responsive read anero'id; andthat the said Letters Patent should be read with these correctionstherein that the same may conform to the record of the case in thePatent Ofiice.

Signed and sealed this 14th day of December, A. D. 1948.

THOMAS F. MURPHY,

Assistant Oommz'ssz'oner of Patents.

August 17, 1948.

